Hybrid drill bit

ABSTRACT

A boring tool having downhole hammered impact elements that present to the bore face from platforms or plateaux of the work face of the tool, such work face having shear cutters able to benefit over the bore face from disruption caused by the impact elements.

FIELD OF INVENTION

The present invention relates to hybrid drill bits.

More particularly the present invention relates to a drill bit (whetherfor purely drilling or whether for obtaining a core) where there is aprofiled face (e.g. any form able to act as a shear cutting bit) able toact in concert with percussive features better able, than the profiledface, to disturb the integrity, or facilitate the removal of theformation of the bore face.

BACKGROUND

In deep-high pressure bore holes, the hydrostatic fluid pressure tendsto hold down the previously fractured drill chips. This has beenpartially offset by using “shear cutting” bits (normally polycrystalline diamond “PDC”—or diamond impregnated bits) which scrape awaythe formation (rather than smashing/crushing the formation as is thecase with roller bits or impact hammers).

However the shear cutters are not suitable for use in very hard rockformations, as these formations easily destroy the cutters.

In such deep-high pressure bore holes (very much deeper than, say, 1500metres) downhole hammers acting on a downhole tool should in theorydrill rapidly, however at such depths there are high downhole pressures.Testing has shown that once the borehole pressure exceeds 1200 PSI therate of production when drilling with fluid hammers decreasessubstantially it is assumed due to chip hold down. While it is believedthat the present invention helps overcome the chip hold down phenomenon,this design has also been shown to have advantages in shallow bore holelow pressure drilling applications.

We propose a hybrid drill bit that combines the impact action associatedwith down hole hammers—which are effective at fracturing the formation,with shear cutting elements which are very effective at scrapingfractured (by the hammer action) rock formations out of the borehole.The hybrid bit is designed in such a way that the shear cutters aresomewhat isolated from the hammer action.

We propose such a hybrid drill bit to have such features rotatabletogether, yet movable relative to each other axially of the rotationalaxis, as well as being able to rotate independently (and randomly) ofthe rotation of the bit body) so that percussive emergent features ofhigh point loading, yet requiring manageable energy inputs to a downholehammer, can break chips free, or fracture the formation to ultimatelyprovide chips, without hydrostatic chip hold-down owing to theirimmediately being scraped away and/or cut away into a flushing fluidflow (e.g. mudflow) to take such scraped away chip material(s) away fromthe formation face.

U.S. Pat. No. 7,546,888 of Shell Oil Company discloses a percussivedrill bit carrying both axial cutters and shear cutters in a mutuallyfixed interrelationship so that the axial cutters bear on the formationface in advance of the shear cutters.

U.S. Pat. No. 7,104,344 also of Shell Oil Company discloses a method ofdrilling into geological formations where there is a use downhole ofboth percussive elements and shear or drilling cutters. There is apercussive movement of a predominant and central percussive part (withplural percussive elements extending to the perimeter) relative to themore outwardly arrayed banks of drilling cutters. The drilling cuttershave the function of a scraping away of the cracked parts of theformation.

The embodiments of U.S. Pat. No. 7,104,344 have, as its percussiveelement, a structure carrying multiple percussive cutters about whichare deployed gangs of drilling cutters. The numbers of percussivecutters greatly outnumber the numbers of drilling cutters.

The arrangements of U.S. Pat. No. 7,104,344, by having the large numberof percussive axial cutters and by having the gangs of drilling cuttersin constant contact with the rock face, has a high energy requirement torender the percussive axial cutters effective owing to a resultant lowpoint loading. Also the multiple percussive cutter structure denies theoption of the drilling cutters extending as arrays, radial or otherwise,to regions close to the axis of rotation.

The arrangements of FIGS. 2 and 4 of U.S. Pat. No. 7,140,344 with ratiosof percussive cutters: drilling cutters of 38:16 and 21:16 respectivelyalso have flushing fluid parts confined well away from the central zonethereby reducing entrainment efficiency from that zone.

Eddison U.S. Pat. No. 7,461,706B2 describes several embodiments, one ofwhich uses emergent impact features in conjunction with either rollingelements—of shear cutters. With this device it is not possible to havethe impact projectiles strategically covering the entire diameter of thedrill face.

In a second embodiment of U.S. Pat. No. 7,461,706B2 a core samplingdevice is described—however with this device, once the central hammerwith (impacting profiles) is withdrawn—the core drilling falls solely onthe shear cutters, which will not survive in hard rock formations—orrelies on rolling elements, which can drill hard rock—but require a highlevel of thrust (weight on bit) to advance into the formation. Thisextra thrust will require extra torque to rotate the bit, this can thenhave the negative consequence of causing a stick/slip reaction which canprematurely destroy drill bits.

A hybrid drill bit of the present invention (whether for hole drilling,core sampling or otherwise) is likely to overcome this problem inseveral ways;

-   -   by using an impact hammer action (through dedicated percussive        features emergent through the shear cutter carrying face) (e.g.        of Carbide or Diamond) that percussively fractures the hard rock        formations—significantly weakening the rock structure.    -   the percussive features are strategically located across the        face of the drill bit, from the centre, to the outer periphery,        this greatly assists in bit design as when used with hammers of        even modest impact force, the impact force can be applied across        a relatively small number of strategically placed percussive        features—thereby still giving significant point loading—or rock        destruction, while allowing ample space to affix the shear        cutting members, which can then remove the fractured formation.    -   A second embodiment will describe a core sampling hybrid bit.        Again the ability to strategically place the percussive features        as required—allows a core drilling bit to be designed whereby        the ring of rock surrounding the core sample is able to be        destroyed by impact and removed in conjunction with shear        cutters, this is particularly important in hard rock mineral        sampling as the shear cutters by themselves would likely not        survive in the hard rock environment without the pre crushing        that the strategically placed percussive features provide. It        also means that unlike the Eddison U.S. Pat. No.        7,461,706B2—high thrust loads and the resultant negative        stick/slip are not required/encountered when core drilling In        either of the embodiments our design offers the ability for the        percussive features to be housed in such a way that as the drill        bit body is rotated (—generally from a surface drive) the        percussive features are free to randomly rotate within their        respective housings. Some of the drilling fluid is allowed to        flow around the percussive features shaft and the bit body        housing—this assists in lubricating/cooling the axially moving        and rotating percussive features.    -   This independent and random rotation of the percussive features        has the significant advantage of helping to avoid flat spot wear        on the impact faces (which leads to premature dulling of the        drill bits). Given that the drill bits can often be many        thousands of meters below ground, the benefits of minimizing        premature bit wear can save considerable time.    -   by using, in concert with such impact hammer action through the        emergent percussive features, a profiled main drill face with        shear cutters (of any shape, or material, or positioned with        positive, negative, or neutral angles of rake, or mixtures        thereof) that can be located in any suitable array, including to        regions close to the axis of rotation, to scrape away or shear        cut the fractured rock more efficiently    -   by using preferably drill fluid jetted preferably through the        profiled main drill face as a flushing fluid (albeit serving        other uses if desired) to the rock formation to assist in        removing the fractured rock from the whole of the rock face.

The present invention is directed to hybrid drill bits (whether fordrilling a bore or for core drilling or otherwise) which incorporatessome of these features or which provides an advantage or at leastprovides a useful choice in the tool choice for rock or downholeformation drillers.

BRIEF DESCRIPTION OF THE INVENTION

In an aspect the invention is a boring tool for use downhole for holeboring or core taking when connected so as to depend and rotate with adrill string about an axis of rotation aligned to that of the drillstring, the tool comprising or including

a body member or assembly (“body”), the body to depend from the drillstring and defining a profiled work face to be presented against thebore face and to accord substantially to the area and shape of the boreface, such bore face to be bounded by a circle if the tool is for holeboring and such bore face to be annular if the tool is for core taking,

shear cutters carried by the profiled work face, and

impact elements, whether of a common component or not, supported by thebody so as to be movable through the work face of the body and able tobe hammered directly or indirectly from behind the work face of the bodyto provide, or be, localised impact emergences beyond localities of theprofiled work face;

wherein said profiled work face defines recessed or non-protuberantregions amongst non-recessed or protuberant regions;

and wherein the localised impact emergences are each from a non-recessedor protuberant region of the profiled work face of the body

and wherein the localised impact emergences and bit features of theprofiled bit will act in concert across the bore face.

Preferably said impact elements are emergent of non-recessed orprotuberant regions of the profiled work face and said shear cutters areon the non-recessed or protuberant regions, the recessed ornon-protuberant regions, or both

Preferably each said impact element can rotate about a reciprocationaxis at least substantially parallel to said axis of rotation.

Preferably the body includes porting to allow a fluid egress.

Preferably the impact emergences are spread about the work face of theimpact elements and the spread involves localities of different radiifrom said axis of rotation.

Preferably shear cutters are on said non-recessed or protuberantregions.

In one option the tool is for core taking and said impact elements areon an at least substantially common radius from said axis of rotationand said sheer cutters act inwardly and outwardly of the locus of thatat least substantially common radius.

Preferably, for that option, said shear cutters are in recessed ornon-protuberant regions of the profiled work face of the body.

In another aspect the invention is a boring tool having downholehammered impact elements that present to the bore face from platforms orplateaux of the work face of the tool, such work face having shearcutters able to benefit over the bore face from disruption caused by theimpact elements.

In another aspect the invention is a hybrid drill bit suitable for usedownhole, for hole boring, the hybrid drill bit comprising or includingan assembly which when associated with a drill string defines, or willdefine,

a profiled bit or bit assembly (“bit”) able to be rotated about an axisof rotation to have an effect on a bore face over its diameter ofoperation, the profiled bit having bit features able to effect, in use,a shear cutting affect, a chip sweeping affect or a scraping affect, orany combination of the affects, and

impact elements, whether of a common component or not, able to behammered directly or indirectly to provide, or be, localised impactemergences beyond localities of the profiled bit;

wherein the localised impact emergences, upon rotation of the profiledbit, and thus the hybrid drill bit, have

(a) plural radiused loci of rotation, or

(b) plural radiused loci of rotation and a location at the axis ofrotation;

and wherein the localised impact emergences and the bit features of theprofiled bit act in concert across said diameter of operation of theprofiled bit.

Preferably said profiled bit is profiled in part by shear cutters orwear resistant members [“shear cutters”] as inserts presenting from abit body.

Preferably said bit body itself is profiled to present both

(i) protuberant regions and

(ii) less protuberant or recessed regions.

Preferably each said impact elements presents, when hammered directly orindirectly, from a said protuberant region.

Preferably said shear cutters present from said protuberant regions.

Preferably fluid outlets are disposed in said bit body in said lessprotuberant or recessed regions.

Preferably the profiled bit is splined to a captive hammering assembly.

Preferably said hammering assembly comprises or includes an annularhammer able to duct fluid.

Preferably a ported member to receive fluid via said annular hammerreceives and conveys the impacts of the hammer to the impact elementsand receive fluid to said outlets.

Preferably said impact elements are individually rotatable relative tosaid profiled bit.

Preferably each impact element is of a profiled bit captive wearresistant material held by or impactable upon by a captive guidedhammerable member.

In another aspect the invention is a downhole tool comprising orincluding

a bit profiled by at least multiple shear cutting inserts or shearcutters (“shear cutters”) able to be presented to a bore face as the bitis rotated, and

multiple impact elements rotatable with the bit yet hammerable directlyor indirectly so as to emerge or further emerge from the bit to act inconcert with the shear cutters;

wherein the shear cutters are arrayed so as, in use as the tool isrotated and the impacted elements are hammered directly or indirectly,to at least substantially fully sweep/shear cut on loci of rotationabout the rotational axis of the bit that will follow disruption of theor a bore face caused by the hammered emergence, or further emergence,of said impact elements that rotate on loci of rotation about therotational axis of the bit to be intermittently disruptive over at leastall of the area of the or said bore face.

Preferably the bit has a bit body with a profiled face presentable to abore face in use, said profiled face having more protuberant regions andless protuberant or recessed regions, the impact elements being emergenteach from an opening through a protuberant region.

Preferably shear cutters as insets are carried by some or all of saidprotuberant regions.

Preferably ports for fluid emergence are provided through some or all ofsaid less protuberant or recessed regions.

In another aspect the invention is apparatus (i.e. hybrid drill bit ordownhole tool) as aforesaid positioned downhole to rotate with a drillstring and provided with a hammering mechanism actuable to directly orindirectly hammer the impact elements.

In another aspect the invention is a hybrid downhole tool able to boreinto a bore face whilst presenting a spread of captive localisedpercussive elements or cutters to the bore face and clearing dislodgedand/or ruptured material(s) of the bore face reliant upon a profiledarray of shear cutters;

wherein the captive percussive elements or cutters despite beingemergent from hammered directly or indirectly to provide, as the tool isrotated, both a radial spread of loci of intermittent percussive actionacross substantially the whole diameter of the effect of the tool.

In still another aspect the invention is a hybrid coring tool suitablefor use downhole for core taking, the tool comprising or including anassembly which when associated with a drill string defines, or willdefine, a profiled bit or bit assembly (“bit”) having an annular profileable to be rotated about an axis of rotation to have an annular affecton a bore face over its annular field of operation, the profiled bithaving bit features able to effect, in use, a shear cutting affect, achip sweeping affect, or a scraping affect, or any combination of theaffects, and

impact elements, whether of a common component or not, able to behammered directly or indirectly to provide, or be, localised impactemergencies beyond localities of the annular field of action of theprofiled bit.

Preferably the localised impact emergences, upon rotation of theprofiled bit, and thus the hybrid coring tool, have

a single radius loci of rotation or plural radiused loci of rotation,yet having inwardly and outwardly of the locus of rotation, or said lociof rotation, shear cutters.

In another aspect the invention is the use of a downhole rotatable toolto have an effect on a bore face on a delimited area being:

(A) an area delimited by a radial distance from the tool's axis ofrotation, or

(B) an annular area delimited between different radial distances fromthe tool's axis of rotation;

wherein the tool is characterised in having a body presenting a profiledface towards the bore face over the delimited area;

and wherein protuberances of the profiled face carry wear resistingshear cutters;

and wherein emergent from passageways opening from said protuberancesare impact elements able directly or indirectly to be hammered toprovide a percussive disruption into said delimited area from whence anyruptured or dislodged material can be cleared from the delimited area bysaid shear cutters and/or the profiled face.

Preferably the use is together with fluid released via and/or to theprofiled face.

In another aspect the invention is a method of removing material from asubterranean face which comprises or includes the steps of rotatingagainst such face a downhole rotatable tool which has an effect on abore face on a delimited area, the delimited area being

(A) an area delimited by a radial distance from the tool's axis ofrotation, or

(B) an annular area delimited between different radial distances fromthe tool's axis of rotation:

characterised in that whilst rotating the tool a profile faced body orassembly (“tool body”) of the tool which has protuberances as plateauregions, both

(i) carries wear resisting shear cutters and

(ii) allows the emergences from each dedicated passageway of passagewaysopening from such plateau regions impact elements that are hammered,said method comprising ensuring such impact elements are directly orindirectly downhole hammered whilst rotating in unison with the toolbody to the affect that the impact elements provide a percussivedisruption into said delimited area of the bore face from whence anyruptured or dislodged material(s) can be cleared from the delimited areaby said shear cutters and/or the profile of the tool body.

In another aspect the invention is a hybrid drill bit (whether for holedrilling, core sampling or otherwise) comprising or including anassembly, or at least an assembly when associated in use with a drillstring, having

a first component (unitary, fabricated or assembled) providing aprofiled face, and

a second component (unitary, fabricated or assembled) to provide orproviding emergent features through and from a dedicated passageway foreach emergent feature from the profiled face of the first component;

wherein relative movement can occur or can be caused (e.g. by ahammering system) between the first and second components such thatemergent features emerge, if not always emerged, and/or emergentfeatures are further emerged from an already emerged condition;

and wherein the emergent features can have a percussive effectresponsive to an appropriate input to the second component (e.g. by sucha hammering system);

Preferably a hammering system can cause said relative movement (whetheractively or inwardly or outwardly, or both).

Preferably a said profiled face is, or includes elements to provide, ashear cutting- or scraping face.

Preferably such shear cutting face or element can be made of anysuitable formation shearing and or cutting compound (e.g. diamond,synthetic diamond, tungsten carbide etc). The rake angle of such shearcutting or scraping face can be positive, negative or neutral, or somemixture of those.

In another aspect the invention is a hybrid drill bit (whether for holedrilling, core sampling or otherwise) comprising or including anassembly, or at least an assembly when associated in use with a drillstring, having

a first component (unitary, fabricated or assembled) providing aprofiled face carrying multiple shear cutting elements and having atleast one outlet for a flushing fluid, and

a second component (unitary, fabricated or assembled) to provide orproviding emergent percussive features through (and not simplyalongside) the profiled face of the first component, the number ofpercussive features being fewer than the number of shear cuttingelements;

wherein relative movement can occur or can be caused (e.g. by ahammering system) between the first and second components such thatemergent percussive features emerge, if not always emerged, and/oremergent features are further emerged from an already emerged condition;

and wherein the emergent features can have a percussive effectresponsive to an appropriate input to the second component (e.g. by sucha hammering system) relative to the first component. Preferably thehybrid drill bit is associated for activation with a magnetic hammeringassembly having interacting magnetic arrays providing a hammering affectresponsive to a rotational relative movement able to be caused betweenthe magnetic arrays.

In respect of either of the preceding two aspects:

-   -   Preferably said profiled face is a shear cutting face.    -   Preferably the profiled face may include shoulders, edges,        relief features and/or the like of a hard material (e.g.        carbides, PDC, etc) able to effect scraping and/or cutting        and/or sweeping for chip removal purposes (commonly referred to        as “shear cutters”).    -   Optionally a PDC or a diamond impregnated material forms part,        if not all, of said profiled face.    -   Preferably said hybrid drill bit has provision for the passage        of a fluid (e.g. drill fluids) to the bore face and/or from the        profiled face.    -   Preferably said emergent features are substantially emergent to        the same extent simultaneously under an action that causes        sufficient relative movement to have them standing proud of each        adjacent part of said profiled face.    -   Preferably said emergent features are protuberances that [when        not retracted and/or forced back] bear on the formation (at        least when fully emergent) in preference to parts of the        profiled face. Optionally the emergent features can be connected        to the reciprocating hammer shuttle so they are actively driven        into and pulled away from the formation face.    -   For example, preferably shear cutting or the like features of        the profiled face preferably follow where it is, or a zone where        it is, an emergent member will likely first have encountered the        intact rock face and had a sufficient percussive effect to        fracture the rock, resulting in less wear on the profiled face        relief feature following that emergent feature, and allow the        profiled face (shear cutters) to survive in hard formations        where they may otherwise be damaged.

In a further aspect the invention consist in a hybrid drill bit havingreliance on features rotatable together yet movable relative to eachother axially of the rotation axis, as a result of energy inputs, of

-   -   (i) intermittently percussively striking the formation with        first wear resisting protuberant features, and    -   (ii) shear cutting, scraping, sweeping and/or the like the        weakened formation and any chips generated by the percussive        action (i.e. of (i)) with second wear resisting features;

wherein the first wear resisting protuberant features can rotate abouttheir own axes yet are emergent of a body or component carrying thesecond wear resisting features.

Preferably the percussive features (i) are features carried so as toemerge, or emerge more proudly, through a profiled face having the otherfeatures (ii).

In a further aspect the invention consist in a hybrid drill bit havingreliance on features rotatable together yet movable relative to eachother axially of the rotation axis, as a result of energy inputs, of

-   -   (iii) intermittently percussively striking the formation with        first wear resisting protuberant features, and    -   (iv) shear cutting, scraping, sweeping and/or the like the        weakened formation and any chips generated by the percussive        action (i.e. of (i)) with second wear resisting features; the        second wear resisting features being greater in number than the        first wear resisting features.

Preferably the percussive features (i) are features carried so as toemerge, or emerge more proudly, through a profiled face having the otherfeatures (ii).

In core drilling variants the number of second wear resisting featuresneed not be greater. See hereinafter where they are shown as about thesame as an option.

In a further aspect the invention consist in a hybrid drill bit havingreliance on features rotatable together, yet movable relative to eachother axially of the rotation axis, as a result of energy inputs, of

-   -   (i) intermittently percussively striking the formation with        first wear resisting protuberant features; and    -   (ii) shear cutting, scraping, sweeping and/or the like any chips        generated by the percussive action (i.e. of (i)) with second        wear resisting features;

wherein the percussive features (i) are features carried so as toemerge, or emerge more proudly, through a profiled face having the otherfeatures (ii);

and wherein the percussive features (i) are fewer in number than thefeatures (ii).

Preferably the hybrid drill bit is associated for activation with amagnetic hammering assembly having interacting magnetic arrays providinga hammering affect responsive to a rotational relative movement able tobe caused between the magnetic arrays. In respect of either of thepreceding two aspects:

-   -   Preferably any suitable form of assembly is contemplated. The        examples hereinafter described with or without reference to the        accompanying drawings are mere examples.    -   Hereinafter described with reference to some of the drawings is        a core sampling form of such a hybrid drill bit. Such a core        sampling form of hybrid drill bit could be incorporated in        apparatus for core sampling.    -   In other forms the hybrid drill bit is for drilling into a hole        against a bore face (e.g. whether steered (directional) or        unsteered and whether upward, horizontal or vertically downward        for any suitable purpose. Preferably it is to be used through        rock or formations that may include rock.    -   Preferably there is provision for a drilling fluid or other        fluid to pass through at least part of the hybrid drill bit.    -   Preferably that fluid passage provision is via the profiled face        which has a plurality of ports appropriately positioned to        provide an efficient outcome.

In another aspect the invention is a hybrid drill bit (whether for holedrilling, core sampling or otherwise) comprising or including anassembly, or at least an assembly when associated in use with a drillstring, having

a first component (unitary, fabricated or assembled) with a profile withplateaux carrying shear cutters thereby providing a shear cutting face,and

plural impact elements extending through the first component andactuable to provide a percussive effect or a pounding functionality;

wherein the first component can sweep and/or shear cut away material(s)disrupted by the plural impact elements thereby to clear the bore face(circular and extending from the rotational axis of the first componentor annular about that rotational axis if a core taking drill bit).

In another aspect the invention is a hybrid drill bit (whether for holedrilling, core sampling or otherwise) comprising or including anassembly, or at least an assembly when associated in use with a drillstring, having

a first component or assembly (unitary, fabricated or assembled)providing a shear cutting functionality which arises from a profiledface carrying multiple shear cutting elements and having at least oneoutlet for a flushing fluid, and

an array of impact elements (unitary, fabricated or assembled) toprovide or providing plural impacts the bore face area, each impactelement area extending through a spread array of passageways of thefirst component or assembly, each for a said impact element, andactuable to provide a percussive effect or a pounding functionality.Preferably the hybrid drill bit is associated for activation with amagnetic hammering assembly having interacting magnetic arrays providinga hammering affect responsive to a rotational relative movement able tobe caused between the magnetic arrays.

Preferably the shear cutting elements outnumber the impact elements.

In respect of either of the preceding aspects:

-   -   Preferably the relative movement of the impact elements relative        to the first component can occur or can be caused by a hammering        system. However the impact elements can be energised by any        suitable means to have the percussive effect or pounding        functionality.    -   Preferably the shear cutting face may include shoulders, edges,        relief features and/or the like of a hard material able to        effect scraping and/or cutting and/or sweeping for chip removal        purposes.    -   Optionally a PDC or a diamond impregnated material forms part,        if not all, of said shear cutting face.    -   Preferably said hybrid drill bit has provision for the passage        of a fluid (e.g. air, gas, liquids) to the bore face and/or from        the shear cutting face.    -   Preferably said impact elements are emergent features, i.e.        having sufficient relative movement to have them standing        sufficiently proud of each adjacent part of said profiled face        to have said percussive effect or pounding functionality.    -   Preferably said impact elements when not retracted and/or forced        back bear on solid rock in preference to parts of the profiled        face.    -   For example, preferably shear cutting features follow where it        is, or a zone where it is, an impact element will likely first        have encountered the intact rock face and had a sufficient        percussive effect or pounding functionality to create stress        fractures within the formation and allow less wear or stress on        the shear cutting relief feature following that impact element.

In another aspect the invention consist in the reliance downhole of theformation-face destructive protuberances of a shear cutting drill bit,the protuberances being repeatedly moved to a proud, or more proud, andpercussive effect condition on the formation-face under the action of adownhole hammer.

In another aspect the invention consist in the reliance downhole of theformation-face destructive protuberances of a shear cutting drill bit,the protuberances being repeatedly moved to a proud, or more proud, andpercussive effect condition on the formation-face under the action of adownhole hammer.

wherein each protuberance can freely rotate about its own axis and/orthe protuberances, as an array, when rotated about the axis of a carrierof the shear cutters, has such percussion affect sufficient for thewhole field of action of the shear cutters.

In yet a further aspect the invention is a hybrid drill bit for coresampling comprising or including

a body defining an annular or near annular face or end (“face”) about apassage to receive the core;

a plurality of shear cutters carried by the body and projecting from theface; and

a percussively driveable bank of percussive elements able to bepercussively emergent or more emergent from the face of the body.

In yet a further aspect the invention is a hybrid drill bit for coresampling comprising or including

a body to be rotated downhole about its axis, the defining an annular ornear annular face or end (“face”) about its axis and about a passage toreceive the core;

a plurality of shear cutters carried by the body and projecting from theface; and

a percussively driveable bank of percussive elements able to bepercussively emergent or more emergent from the face of the body;

wherein any one or more of the preferments or options herein describedapplies.

In another aspect the invention is any hybrid drill bit satisfying theearlier mentioned criteria where a downhole hammer (air, fluid,magnetic, etc) can repeatedly thrust out, to percussive effect, multipleprotuberances. Preferably the protuberances as a gang movesimultaneously. These hammerable protuberances may or may not bemechanically driven into and out of the drill bit housing.

Preferably the protuberances are an array disposed in conjunction withshear cutting features not repeatedly thrust out.

In a further aspect the invention consists in, as an assembly, ahammering arrangement for use downhole as part of a drill string orwithin part of a drill string, and a hybrid drill bit of any of thekinds herein described. In yet a further aspect the invention consistsin a method of drilling and/or core taking which involves the operativeuse of a hybrid drill bit in accordance with the present inventionand/or any of the other assemblies of the present invention. Thisconcept has many advantages over conventional bits (either shear cutterbits or impact bits) the advantages are:

-   -   The shear cutters do not suffer from impact from the hammer        action    -   Cause the formation to fail in compression, tension and shear.    -   The impact forces from the hammer can be spread over relatively        few impact teeth—the result is deep and broad fracturing of the        formation    -   A low energy requiring magnetic hammering arrangement is all        that is required for effective percussive action.    -   The scraping action of the shear cutters is not confined to a        small annulus set out from the rotational axis.    -   The elimination of the “stick/slip” phenomenon associated with        aggressive shear cutters    -   The shear cutters become effective in very hard rock    -   Low up hole shock levels    -   Propensity to drill straighter bores due to slow drill        string/bit rotation speeds of typically less than 100 rpm—this        is especially true when used in core drilling applications when        compared to diamond core drilling which often requires 1000+RPM    -   Extends bit life

The advantages when used in a core drilling or sampling application are:

-   -   Fast accurate core sampling through a broad variety of        formations    -   The impact hammer pre crushes an outer ring of the formation    -   The shear cutters scrape out the damaged rock and/or debris from        the formation    -   The shear cutters do not suffer from impact stresses (which they        are vulnerable to)    -   Allows shear cutters to survive in hard rock or other formations    -   Drill fluid is jetted to the formation in the normal way, to        assist in removing the fractured debris    -   Propensity to drill straighter bores    -   Extends bit life

As used herein “drill”, “drilling”, etc relate to a rotary action ofwhole or part of apparatus able to remove material from a rock surfaceand/or bore face.

As used herein the term “profile face” in no way refers to its method offormation. It refers to there being sufficient relief features (whetheroutstanding and/or inset from a radial plane or otherwise of the hybriddrill) presentable to the bore face.

As used herein “emergent”, “proud”, etc includes any sufficientemergence further emergence, proudness, or further proudness to achievean advantageous percussive or pounding affect on the formation.

As used herein “formation” or “rock formation” refers to any formationthat requires fracturing whether it's rock like or not.

As used herein reference to “across the diameter” or equivalent words(whether in respect of the whole distance or just those parts to accordto an annulus) does not mean aligned on the same diameter. It includesany spread of the impact elements or any spread of the shear cutterswhere, collectively, when one considers the loci of action of each,generates a sufficient sequence of concentric circular loci equivalentto that which would also occur were the spread aligned on a commondiameter passing through the axis of rotation of the whole or annular(or equivalent) profiled work face.

Reference herein to a “profiled work face” or other reference to the“profile” of the body to carry the shear cutters and to allow areciprocal emergence (or other emergence) of the impact elements orfeatures may include

-   -   (A) recesses, valleys or “junk slot” like features whether        single ended, or as shown in the drawings, doubled ended and        whether, as shown, or not, with a dog leg form.    -   (B) non-recesses, platforms, plateaux or protuberances of any        layout and whether or not of single or more types, the figures        in some instances showing as options, in no way limiting, where        some are discrete lands and others meander somewhat. Preferably        the layout is such that over a rotation of the tool, all areas        from the centre, or near the centre, and out to near the maximum        circumference of action by the shear cutters and/or impact        elements/features will be covered by such non-recesses,        platforms, plateaux or protuberances.

It matters not whether the surfaces of the general region of each suchforms (i.e. (A) or (B), or both) are flat, arcuate, undulate, textured,or other. Preferments include the surface forms shown in the figures butare not to be limited thereby.

As used herein the term “(s)” following a noun means one or both of thesingular or plural forms.

As used herein the term “and/or” means “and” or “or”. In somecircumstances it can mean both.

A BRIEF DESCRIPTION OF THE DRAWINGS

A preferred form of the present invention will now be described withreference to the accompany drawings in which

FIG. 1 is one embodiment of hybrid bit assembly (the bit rotates counterclockwise when viewed from the boreface) in accordance with the presentinvention, such a hybrid bit assembly comprising recesses andprotuberances (plateaux) adapted to allow the reciprocal hammeredemergence from the protuberances and bore face returned retreat ofimpact elements, such a profile bit preferably being rendered morefunctional not only by the inherent profile of the body, but also by theinsetting of the wear resistance shear cutters to be describedhereafter, and by fluid porting,

FIG. 2 is a section at 120° on GG with respect to FIG. 1, such asectional view being through three of the impact elements shown tonumber (this is in no way critical) seven in the view shown in FIG. 1,FIG. 2 showing the hammer assembly splined and retained to a main bodymember of the profile bit,

FIG. 3 is a similar section to that of FIG. 2, but this time of the 120°section at LL which is in the recesses, but does cross a plateau, such asection LL passing through two of the six fluid outlet ports shown,

FIG. 4 shows an isometric view, with some cutaway to show a spline, ofanother version of hybrid drill bit (i.e. different in profile of thebit body) but still having a mixture of inset fitted shear cutters onplateau regions and having impact elements able to be hammered to anemergent/more emergent condition (preferably from the plateaux orprotuberant parts of the profiled bit) and having ports for fluidoutlet, FIG. 4 showing some cutaway to reveal a spline, (required whenhybrid bit is used in conjunction with a magnetic hammer-preferred form)

FIG. 5 shows still a further embodiment of a hybrid drill bit, this onehaving greater similarity to the inset provided profiled bit of FIGS. 1to 3, but not exactly the same, FIG. 5 showing protuberant impactelements, liquid ports and plural shear cutters of different types,

FIG. 6 is an isometric view of a preferred form of a core taking tool inaccordance with the present invention, this one showing a mixture ofshear cutters of a profiled annulus or providing and/or part providingpart of the profile of such an annulus, there being shown three, but itcould be any number, impact elements able to hammered so as to beemergent from the condition shown in FIG. 6,

FIG. 7 is the core taking apparatus of FIG. 6, but with the impactelements emerged fully or more fully or more emergent than as in FIG. 6,

FIG. 8 is a front elevational view (e.g. as if from the bore face fromwhich a core is to be taken) of the core taking apparatus of FIGS. 6 and7,

FIG. 9 is a sectional view A-A with respect to FIG. 8 (i.e. of theapparatus of FIGS. 6 to 8) showing an emergent impact or percussiveelement,

FIG. 10 shows a shear cutter acting alone,

FIG. 11 shows an impact element (angling optional) acting in concertwith a shear cutter, and

FIGS. 12A to 12E show how an element as a shear cutting face or scrapingface (e.g. of diamond, synthetic diamond, tungsten carbide, or the like)can be provided obliquely to provide a positive rake angle better ableto uplift material shown as being fractured prior to uplift in thedrawing sequence.

DETAILED DESCRIPTION OF THE INVENTION

In its preferred forms of the present invention any suitable form ofhammer can be used.

Reference previously to “hammers” or “hammering” or “hammering systems”is not restricted to hammering systems of a magnetic interaction typereliant upon our creating a shuttling relativity between interactivemagnetic arrays. Indeed any form of suitable hammering apparatus can beused e.g. eccentric, hydraulic, downhole and/or uphole provided it has adownhole affect. Particularly advantageous types of hammering apparatusare those of typified by our magnetic hammering systems ofPCT/NZ2008/000217 (WO 2009/028964) and PCT/NZ2005/000329 (WO2006/65155).Or indeed even our PCT Application No. PCT/NZ2011/000123(WO2012/002827).

Other suitable downhole forms of hammer can also be used, preferablythose that are pneumatically or fluid driven.

The embodiment of the FIGS. 1 to 3, but with some reference to otherdrawings will now be described.

FIG. 1 is an example of a full face hybrid bit, the geometry is genericin nature—but would typically include plateaux (or platforms) (2,3) forshear cutters (6), whether of an identical or varied type, that arestrategically positioned as profile features across the diameter of thebit. It would also include areas for fluid jets (7), and valleys orrecesses (4)—commonly known in the industry as junk slots that assistwith the removal of the rock cuttings. In addition, the impact elements(8) are also strategically placed across the full diameter of the bit tocrush/fracture the formation—allowing the shear cutters correspondinglyto scrape away the damaged material.

As shown in FIGS. 1, 2 and 3 the moulded, machined, or otherwise formedcomponent or body 1 has a profiled face as a profiled work face whichitself is further profiled by the fixing or insetting of the shearcutters 6 (i.e. wear resistant cutting/sweeping/scraping components).

The fluid outlets 7 provide an outlet for fluid (e.g. drilling mud)directed to the rock face to help remove fractured rock via junk slots4, Whether magnetic hammer systems or non magnetic hammering systems areused [e.g. eccentric, hydraulic, pneumatic or other,] in each case,preferably there is a hammering component 9 (FIG. 2) able to act upon animpact plate 10 (in some embodiments it may be advantageous to have thehammer 9 impact directly to the reciprocatable members 11 & 8) so thatthe hammering impact, conveyed by hammer 9 into the impact plate 9,affects reciprocatable members 11 able to act upon cutters 8 of theimpact elements, (8&11 may be a common component e.g. carbide). Suchcutters 8 despite being captive in the body 1, are free to move bothaxially and rotationally. Preferably 8 and 11 may be interconnected ornot. If connected or unconnected freedom to rotate is desirable. Suchrotation is caused by the rotation of the bit body 1—normally rotatedfrom a surface drive causing 8/11 to rotate randomly as a consequence ofthe action of the rock face on the individual cutters during the courseof use

Shown through the hammer region 9 (FIG. 3) is a fluid passageway 12 thatfeeds via passageways 13 in the impact plate 10 through a communicationchamber 14 to the fluid outlet ports 7.

As can be seen, a sleeve member 15 (as part of the drill string and/orits casing sequence) can be located on the hammer 9 by a ring member 16and be adapted to keep captive to itself, on an interacting spline 17,the bit body 1.

The components 19, 10, 11, 15 and 16 can be any suitable material e.g. asuitable steel. The impact parts 8 can be of a shock resistant, wearresistant material e.g. a hardened steel, but can, in somecircumstances, be of hardened steel, tungsten carbide, diamond etc.

Persons skilled in the art will appreciate how the function of themembers 8 as impact or percussive elements or cutters is to createstress waves of a rock destructive kind in the formation of the boreface. It is not their function to hold the elements 6 from the boreface.

FIG. 4 shows a slightly different embodiment (when used with a magnetichammer) to that of FIGS. 1 to 3. Nonetheless there is a casing 14 toform a part of a drill string and to spline onto a spline 15 of a hammer16. The hammer 16 is to act via an impact member 17 onto each of theprotuberant components 18 of the plateau regions 19 and to act inconcert with shear cutters 20. These cutters in effect cover all of thearea, or at least substantially all of the area, to be disrupted. Otherimpact elements 21 can be strategically placed as required across thefull diameter of the drill bit.

Any suitable spread and interrelationship of numbers of impact elements18/21 to non impacting shear cutting, sweeping, etc components 20 can beutilised provided that, in preferred forms, there is a sufficientdisruption of a face as a result of the repeated impacts over severalradial loci about the axis of rotation of the tool and a sufficientshear cutting and sweeping of the released or ruptured materials acrossmost, if not all, of the effective face of the profile drill head withits impact elements to achieve full clearance.

It is to be noted that the shear cutters extend preferably around theedge of the actual bore face to provide some gauge cutting affect aboutthe face being achieved with the majority of the shear cutters.

Shown also are potential outlets (junk slots) to allow the cuttings tobe removed from the drill face (e.g. provided in recesses 22)

FIG. 5 shows a bit to rotate anticlockwise (viewed from the top down) soas to present shear cutting elements 23 (e.g. of diamond, syntheticdiamond, tungsten carbide, or other suitable material) at a positiverake angle (owing to its facial and leading edge presentation whetherarising from its shape or its oblique mounting, or some mixture ofboth). The profile features of the bit of FIG. 5 are to operate so thatthe shear cutting elements 23 act as in FIGS. 12A to 12E after an impactelement 24 weakens the formation.

The disadvantage of having a negative angle of rake on the shear cuttersor scrapers is that in deep hole high pressure applications, having anegative angle on the shear cutters may tend to push the cuttings backdown and/or against the formation. In such situations, it is anadvantage to provide the shear cutters or scrapers with a positive angleof rake that can aid (as shown in FIGS. 12A to 12E) in lifting and/ormoving the cuttings in a more upwards direction thereby increasingdrilling efficiency. FIGS. 6 to 9 show a preferred form of core takingin accordance with the present invention. For that purpose it is a bitto provide an annular cut so that a central opening within the annuluscan be used for the uptake of the core in any suitable known manner.

In typical core sampling drilling (as required to gather informationabout sub surface formations) a hollow centred drill bit (core bit)normally covered with shear cutting elements such as diamond (syntheticor natural) is rotated at very high speed (normally from a surfacedrive) and gently advanced into the formation. The resulting core sampleis pushed into a core barrel (a hollow tube) normally several metreslong. Once the core barrel is full. The core sample and core barrel arenormally pulled to surface via a wire cable—through the centre of thehollow drill rods—while leaving the drill rods in the ground (which forma temporary casing and stop the drill hole from collapsing) the coresample is removed at surface and the core barrel is lowered back downthrough the hollow drill rods by a wire line to continue the samplingoperation

This approach works well, except in very hard formations—where thediamond core bits suffer excessive wear—or progress is very slow. Thisproblem is exacerbated in mixed formations where the rapidly spinningdiamond bit can easily be destroyed if an unexpected hard formation isencountered.

What we propose is a core bit to be used in conjunction with a hammer(of any type) that has impact profiles strategically placed around thepartial face of the core bit, which under the influence of the hammercrush and fracture the ring of rock to be removed—allowing the shearcutters to remove the fractured rock efficiently, while being (somewhat)isolated from the hammer impact.

This approach allows diamond shear bits etc to survive in hard rockenvironments and drill rapidly—even with relatively slow drill stringrotation (which also helps minimise wear on rill rods etc)

FIGS. 6 to 9 show a main body a name body 25 presenting a profiledannulus 26 towards what will be the bore face. A person skilled in theart would appreciate how the body 25 (whether with splining or not) canassociate with a hammer yet be rotatable with the drill string to beconnected, for example, over or under region 27.

The profiled annular face 26 as shown shows plateaux 28 as part of theprofile of the member 25 or a fabricated member connected thereto.Emergent from these are the impact elements 29 of which three (example)are showing, each more or less on a common radius about the centralradius of the annular structure.

Disposed in less protuberant regions are ports 30 to allow the egress ofa fluid (e.g. drilling mud or the like). Alternatively, or additionally,there can be some release of fluid internally of the core taking cavity31.

Shown to co-act with each protuberant emergence 29 (each shown emergedin FIGS. 7 and 9) are shear cutting wear resistance members 32. Theshear cutters can be of any geometry and any suitable material and theseare staggered on different radii to the common or similar radii of eachimpact element 29.

In alternative forms, there can be some radial variation of location ofthe passageways in which each member 29 locates so that they do notdescribe intermittent impact hits on the same rotational axis as theircommon locus.

Flanking internally and externally of this common locus are the loci ofaction of the more numerous share cutting wear resistant elements 32.These can be a suitable material of any of the kinds previouslydescribed.

Any suitable arrangement can be provided for the hammering of the endregion 33 of the carrying pins or rods or other form of members 34 whichcarry an impact resistant material 35 as the or part of each impactelement 29.

Preferably each impact element 29 has the material 35 fixed to member 34and member 34 is held captive, for example by a restriction profile 36,to the component 25. Its end to the right in FIG. 9 (the end 33) is tobe available for action directly or indirectly by the hammer. A suitablehammer mechanism again is an annular hammer. For example of the typepreviously described able to act through an annular interposed member.

Any suitable porting arrangement for fluid to outlet 30 can be providedincluding from within the cavity 31.

A variation will be noted between the embodiments of a tool that is toclear a full circular region about the axis of rotation when compared tothat that is to clear an annulus only.

For the annulus clearing required for a core taking apparatus preferablythe shear cutters are on loci to flank internally and externally theimpact element locus of action, but nevertheless have an effect onmaterial fracture, ruptured, dislodged, etc, by the impact elements.

For the non annular arrangements of FIGS. 1 to 4, preferably there is astaggering of the impact elements at different radial distances withrespect to the axis of rotation of the overall bit assembly yet,nevertheless, a preferably more numerous provision of shear cutters suchthat there is a sufficient number of shear cutters (e.g. of type 6) toclear the direct face as well as additional shear cutters 6′ to assistfurther in expanding and clearing material.

What is highly preferable is that all impact elements whether of theembodiments of FIGS. 1 to 3, 4, 5 or 6 to 9 have the impact elements8/11, 18, 21, 29, 35, 35/34 rotatable about their own axis preferablyaligned to the rotational axis of the overall apparatus. This preventslocalised wear on the impact face. This is easily achieved by havingeach impact element captive yet rotable on its own longitudinal axis inits guide but able to be struck directly or indirectly by the hammer(e.g. through a common struck member i.e. hammerable member).

The embodiments shown enable high point loading of the gang or array ofpercussive elements, choice of how they are arrayed through the shearcutting assembly, choice of array of the shear cutting elements(including into at least near the centre), a profiling of the face toallow flushing fluid porting from at least one recess, selectivity ofmode of operation when coupled to a (preferably magnetic) hammeringsystem able to be active/deactivated despite its preferred downholedisposition, etc.

Persons skilled in the art will appreciate that the embodimentsdescribed are just some of many different ways to achieve the in concertfunctionality between an impact element and a shear cutting feature.

1. A boring tool for use downhole for hole boring or core taking whenconnected so as to depend and rotate with a drill string about an axisof rotation aligned to that of the drill string, the tool comprising orincluding a body member or assembly (“body”), the body to depend fromthe drill string and defining a profiled work face to be presentedagainst the bore face and to accord substantially to the area and shapeof the bore face, such bore face to be bounded by a circle if the toolis for hole boring and such bore face to be annular if the tool is forcore taking, shear cutters carried by the profiled work face, and impactelements, whether of a common component or not, supported by the body soas to be movable through the profiled work face of the body and able tobe hammered directly or indirectly from behind the profiled work face ofthe body to provide, or be, localised impact emergences beyondlocalities of the profiled work face; wherein said profiled work facedefines recessed or non-protuberant regions amongst non-recessed orprotuberant regions; and wherein the localised impact emergences areeach from a non-recessed or protuberant region of the profiled work faceof the body and wherein the localised impact emergences and bit featuresof the profiled bit will act in concert across the bore face.
 2. Thetool of claim 1 wherein said impact elements are emergent ofnon-recessed or protuberant regions of the profiled work face and saidshear cutters are on the non-recessed or protuberant regions, therecessed or non-protuberant regions, or both.
 3. The tool of claim 1 orwherein each said impact element can rotate about their ownreciprocation axis.
 4. The tool as claimed in claim 3 wherein saidreciprocation axis is at least substantially parallel to said axis ofrotation of said tool.
 5. The tool of claim 1 wherein the body includesporting to allow a fluid egress.
 6. The tool of claim 1 wherein theimpact emergences are spread about the work face of the impact elementsand the spread involves localities of different radii from said axis ofrotation.
 7. The tool of claim 1 wherein shear cutters are on saidnon-recessed or protuberant regions.
 8. The tool of claim 1 wherein thetool is for core taking and said impact elements are on an at leastsubstantially common radius from said axis of rotation and said sheercutters act inwardly and outwardly of the locus of that at leastsubstantially common radius.
 9. The tool of claim 1 wherein said impactelements are rotatable through the profiled work face of the body.
 10. Ahybrid drill bit suitable for use downhole, for hole boring, the hybriddrill bit comprising or including an assembly which when associated witha drill string defines, or will define, a profiled bit or bit assembly(“bit”) able to be rotated about an axis of rotation to have an effecton a bore face over its diameter of operation, the profiled bit havingbit features able to effect, in use, a shear cutting affect, a chipsweeping affect or a scraping affect, or any combination of the affects,and impact elements, whether of a common component or not, able to behammered directly or indirectly to provide, or be, localised impactemergences beyond localities of the profiled bit; wherein the localisedimpact emergences, upon rotation of the profiled bit, and thus thehybrid drill bit, have (a) plural radiused loci of rotation, or (b)plural radiused loci of rotation and a location at the axis of rotation;and wherein the localised impact emergences and the bit features of theprofiled bit act in concert across said diameter of operation of theprofiled bit.
 11. The hybrid drill bit of claim 9 wherein said profiledbit is profiled at least in part by shear cutters or wear resistantmembers [“shear cutters”] as inserts presenting from a bit body.
 12. Thehybrid drill bit of claim 10 wherein said bit body itself is profiled topresent both (i) protuberant regions and (ii) less protuberant orrecessed regions.
 13. The hybrid drill bit of claim 9 wherein fluidoutlets are disposed in said bit body in said less protuberant orrecessed regions.
 14. The hybrid drill bit of claim 9 wherein theprofiled bit is splined to a captive hammering assembly.
 15. The hybriddrill bit of claim 13 wherein said hammering assembly comprises orincludes an annular hammer able to duct fluid.
 16. The hybrid drill bitof claim 14 wherein a ported member to receive fluid via said annularhammer receives and conveys the impacts of the hammer to the impactelements and conveys received fluid to outlets of the bit body.
 17. Thehybrid drill bit of claim 9 wherein said impact elements areindividually rotatable relative to said profiled bit.
 18. The hybriddrill bit of claim 9 wherein each impact element is of a profiled bitcaptive wear resistant material held by or impactable upon by a captiveguided hammerable member.
 19. A downhole tool comprising or including abit profiled by at least multiple shear cutting inserts or shear cutters(“shear cutters”) able to be presented to a bore face as the bit isrotated, and multiple impact elements rotatable with the bit yethammerable directly or indirectly so as to emerge or further emerge fromthe bit to act in concert with the shear cutters; wherein the shearcutters are arrayed so as, in use as the tool is rotated and theimpacted elements are hammered directly or indirectly, to at leastsubstantially fully sweep/shear cut on loci of rotation about therotational axis of the bit that will follow disruption of the or a boreface caused by the hammered emergence, or further emergence, of saidimpact elements that rotate on loci of rotation about the rotationalaxis of the bit to be intermittently disruptive over at least all of thearea of the or said bore face.
 20. The tool of claim 18 wherein the bithas a bit body with a profiled face presentable to a bore face in use,said profiled face having more protuberant regions and less protuberantor recessed regions, the impact elements being emergent each from anopening through a protuberant region.
 21. The tool of claim 19 whereinshear cutters as insets are carried by some or all of said protuberantregions.
 22. The tool of claim 19 wherein ports for fluid emergence areprovided through some or all of said less protuberant or recessedregions.
 23. The apparatus of claim 9 positioned downhole to rotate witha drill string and provided with a hammering mechanism actuable todirectly or indirectly hammer the impact elements.
 24. The apparatus ofclaim 22 positioned downhole to rotate with a drill string and providedwith a hammering mechanism actuable to directly or indirectly hammer theimpact elements.